A conventional heating, ventilation, and air conditioning system (HVAC systems) for a vehicle utilizes one or more ducts mounted under the vehicle's instrument panel to receive a stream of air from the HVAC system's blower motor and to deliver the stream of air to various locations throughout the cabin of the vehicle to cool and/or warm a vehicle occupant. A register is typically located at the terminus of the duct. The register commonly includes pivotable louvers that permit an occupant to selectively direct the stream of air as desired.
While the above described conventional arrangement for delivering the stream of air from the blower motor to the cabin of the vehicle is adequate, there is room for improvement. For example, the ducts add weight to the vehicle and consume space below the dash board. That space must be shared with other vehicle components such as cross-car beams, air bags, and wiring harnesses, to name just a few. Because these components compete for a limited amount of space, the ducts may need to take on a convoluted path, adding material costs, weight, and complication to the molding process. Additionally, the registers add complication by requiring a relatively high number of moving parts. If the ducts and registers could be eliminated from the HVAC system, it would greatly diminish the weight, cost, and complication of the HVAC system.
An earlier attempt to eliminate the ducts as a means for delivering a flow of air to the vehicle occupant was taught by Biasiotto et al. in U.S. Pat. No. 7,815,498 (hereinafter, “Biasiotto”). Biasiotto teaches an HVAC system wherein a flow of air is routed to a forward portion of a vehicle's dash board and then exhausted into the vehicle's cabin. At the exhaust outlet, the flow of air encounters both the vehicle's wind shield and the vehicle's dashboard. A scientific principle that is well known in the HVAC art is the Coanda effect. The Coanda effect is the tendency of a fluid jet to be attracted to a nearby surface. As a result of the Coanda effect, a portion of Biasiotto's airflow will adhere to, and travel along, the windshield while another portion of the air flow will adhere to, and travel along, the dashboard. In this manner, Biasiotto provides a cascading flow of air that rolls over the upper surface of the dash board and then pours onto the vehicle's occupant.
However, Biasiotto provides no guidance for the cascading flow of air as it rolls from the forward edge of the dashboard rearward to the passenger. Consequently, the flow of air may diffuse laterally as it rolls along the upper surface of the dashboard and, as a result, the cooling or heating effect of the flowing air may be greatly diminished. Additionally, Biasotto relies exclusively on the Coanda effect as a means by which to keep the cascading flow of air entrained to the upper surface of the dashboard. However, as the cascading flow of air travels from the front of the dashboard to the rear of the dashboard, its rate of flow will decrease and the strength of the Coanda effect will correspondingly diminish, allowing an increasing amount of the flowing air to stagnate and diffuse into the ambient air of the vehicle's cabin. This will diminish the ability of the flowing air to heat and/or cool the vehicle occupant.
Accordingly, it is desirable to provide an air distribution arrangement for use with a vehicle HVAC system that eliminates the need for ducts to deliver a stream of air to the vehicle occupants. In addition, it is desirable to configure such an air distribution arrangement so as to address the limitations of the system taught by Biasotto. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.